Idler Arm Bolts - Tap size???
I have a 2003 F-150 with a 4.2L V6. I noticed during my last oil change that the idler arm grease boot was cracked, so I recently purchased a new one.
The 2 bolts that hold the idler arm to the frame came out just fine. But when it came time to attaching the new idler arm, I found it IMPOSSIBLE to screw the upper bolt in all of the way.
I figured that I needed to use a tap to clean up the existing tapped hole. So I measured the OD of the bolt with a digital caliper to be .625" OD. I have a thread pitch gage and measured the thread pitch to be 13 threads per inch.
I went to Autozone, and the only close thing that they had to .625-13 was the tap in a Fix-a-thread kit for .500-13 threaded inserts. The tap itself is about .607-13 (used for .500-13 "helicoils"), so I figured that this would be sufficient. There is no such thing as a .625-13 tap on Mcmaster Carr, MSC, Northern Tool, etc. So I cleaned out the thread with the .607-13 tap. The tap encountered some resistance in the same area that I encountered resistance, and it appeared to do a great job cleaning out the hole.
So I tried to screw the bolt back into the upper hole and I found that it is still IMPOSSIBLE to screw the bolt in all of the way. I have about 3/8" left before the bolt head bottoms out on the idler arm. I can see the opposite end of the hole from the right wheel well. I shot some lubricant in there...still no success.
So does anybody know the tap size for this hole???? Is it metric? When I converted .625-13 to metric, I did not see to find any decent matches.
Thanks in advance.